Waterproof and punctureproof paper



Oct. 9, 1934 L. G. COPEMAN 1,975,329 WATERPROOF AND PUNCTUREPROOF PAPER Filed April 8. 1932 INVENTOR.

ATTORNEY.

i" fn" W UNITED STATES PATENT cerros.

WATERPROOF AND PUNCTUREPROOF PAPER Lloyd G. Copeman, Flint, Mich., assignor to Copeman Laborat ries Company, Flint, Mich., a corporation o Michigan Application April i? 1932, Serial No. 604,028

s claims;

This invention relates to waterproof and punctureproof paper, and has to do particularly with an improved moisture-proof paper for bag manufacture and general wrapping purposes.

Heretofore in the manufacture of moistureproof paper it has been the practice to use two sheets of paper with an intermediate layer of moisture-proof material such as asphaltum, a

waterproof paste of caoutchouc and wax, or sheet rubber and cement, as evidenced by the patents to Crane No. 66,302 of 1867, Johnson No. 229,045 of 1880, and Barstow et al., No. 1,753,281 of 1930. The primary object of substantially all of these prior art structures has been the production of a rather tough paper because of the three layers, and a moisture-proof paper, and while such papers have served their purpose in this respect they have practically all had the disadvantage of being relatively expensive and also of being moisture-proof only if not subjected to rough usage.

It is the object of the present invention to provide an intermediate layer of moisture-proof material for papers of this general type, which material is relatively inexpensive, easy to apply, and which is so thin and elastic as to be readily stretched and distorted when the paper is punctured so as to form a positive moisture-proof seal, even if the paper is punctured or damaged. I accomplish this result by applying a layer of latex between the two layers of paper, the paper being pressed or folded together while the latex is still in plastic or tacky form whereby it acts as an adhesive and the paper, because of its porosity, at the same time assisting in the setting up of the latex into a thin homogeneous lm of rubber. The thin layer of rubber deposited from the latex, in addition to keeping the paper moisture-proof under rough usage and even if subjected to puncture, also provides a tough pliable paper of much less weight and Abulkiness than heretofore used.

In the drawing:

Fig. 1 is an elevation, partly in section, of an automobile crated in the usual manner and having the immediate body coated with paper treated according to the present invention.

Fig. 2 is a more or less diagrammatic View illustrating one process of forming latex bonded paper.

Fig. 3 is a sectional View of paper fabricated in accordance with the present invention.

Fig. 4 is a fragmentary sectional view illustrating the manner in which the layer of rubber deposited from latex seals the paper at any point of breakage.

Fig. 5 is a sectional view illustrating the adaptability of my latex bonded paper to the covering of a portion of an automobile.

Fig. 6 is a sectional View of a modied form of paper where the exterior surfaces are coated with rubber deposited from latex.

My new article of manufacture may best be described by referring to the preferred process of manufacturing the same as disclosed in Fig. 2. A bath 2 of latex may be maintained at a suitable level and any suitable concentration. For most grades of moisture-proof paper, the latex or aqueous dispersion of rubber will be of a relatively thin solution and, of course, always suflicient to form a homogeneous layer oi rubber when vaporized. One continuous layer oi' paper 3 may be fed over a suitable roller 4 having a portion oi its surface constantly immersed in 7 the bath of latex 2. The roller 4 revolving in the bath of latex will cause an even layer ci such latex to be applied to the underside of the continuously moving roll of paper 3 and this latex being in plastic condition will readily adhere to the underside of the paper.

A second roll of paper 5 may be moved into contact with the exposed latex so that the two layers of paper with the intermediate layer of latex may be joined together and fed as a unit to the pressure rolls 6. The pressure rolls 6 will cause the layers of paper and rubber latex to be uniformly and smoothly joined together, the pa per absorbing a large amount of the water from the latex solution so as to quickly accelerate the setting up of the latex into a uniform sheet of rubber. Thus the latex in itself acts inherently as an adhesive causing the two layers of paper to be bonded together and the paper in turn eausing the aqueous dispersion of latex to quickly deposit and set up.

The latex when confined between the two layers of paper will set up almost immediately thus cutting down the time of fabrication, and making it possible to fabricate the moisture-proof paper at the factory o1' place of wrapping or other application.

When my novel moisture-proof paper is used in connection with bags, for instance, cement bags, a material saving will be effected because it is well known that in the handling of cement bags, regardless of the toughness of the paper used, many of the bags are subjected to rough usage and puncturing, with the result that the cement leaks out very readily. By using cement invention, the bags may be bumped up against a relatively sharpgbject, as shown at 7 in Fig. 4, and While the paper itself may"bebroken, as at 8, the thin layer ofrlatex deposited rubber will have suiiicient elasticity as to be distorted a relatively great extent and still preserve the seal. Thus while the thin layer of latex deposited rubber toughens and reinforces the paper, its greatest asset is its sealing of the paper even when punctured.

Very thin paper may be used in carrying out this invention because the homogeneous layer of latex deposited rubber adds great tensile strength to the finished article. To increase the moistureproof and punctureproof qualities of the paper, one or both sides may be coated with an additional layer or layers of latex 9 as shown in Fie. 6. i'

It will thus be seen that I have produced a moisture-proof and puncture-proof paper which may be used for forming most any kind of a package from a bag to the wrapping of automobiles. It is particularly adapted to both bags and automobiles where a positive moistureproof wrapping is desired. The resulting article, though tough, is quite flexible and pliable so as to in itself give way to any knocks or abrasions. However, instead of rupturing as would be the case with paper having an intermediate layer of asphaltum or rubber paste or sheets of rubber, the thin layer of latex deposited rubber is highly elastic and will permit almost any article to protrude through the paper itself several inches without rupturing the rubber. Thus the layer of rubber between the two sheets of paper in my new composite sheet is highly elastic as compared to mere flexibility.

What I claim is:

1. As a new article of manufacture, a co posite sheet for use in making moisture-proof and substantially punctureproof packages, said sheet including an intermediate layer of highly elastic rubber deposited from an aqueous dispersion of rubber, and a layer of paper adhering to the respective sides of said intermediate layer but being released in part from said rubber when broken by an object whereby said released rubber will follow the contour of the object.

2. As a new article of manufacture, a composite sheet for use in making moisture-proof and substantially punctureproof packages, said 'l bags constructed in accordance with the present sheet including a layer of fibrous material, a layer of rubber deposited from an aqueous dispersion of rubber directly adhering to the layer of fibrous material, and a second layer of fibrous material directly adhering to the other side of said 'layer of rubber, said layer of rubber being highly elastic and permitting of great inherent distortion and being separated in part from the fibrous material in the event an article protrudes throng the normal surface of the package.

3. As a new article of manufacture, a composite sheet for use in making'moisture-proof and substantially punctureproof packages, said sheet including a layer of paper, a layer of rub- Der deposited from an aqueous disperson of rubber directly adhering to the layer of paper, and a second layer of paper directly adhering to the other side of said layer of rubber, said layer of rubber being separable in part from the paper and highly elastic and permitting of great inherent distortion in the event an article protrudes through the normal surface of the package.

4. As a new article of manufacture, a composite sheet for use in making moisture-proof and substantially punctureproof packages, comprising two sheets of paper bonded together solely by a homogeneous layer of highly elastic rubber deposited from a relatively thin concentration of an aqueous dispersion of rubber, said layer of rubber being separable from said paper by an object breaking through the paper,

5. As a new article of manufacture, a moisture proof laminated container comprising inner and outer walls of paper and an intermediate thinelastic layer of rubber deposited from an aqueous dispersion of rubber, said intermediate layer of rubber being normally bonded to said outer layers of paper but being releasable from said inner and outer layers of paper by an object breaking through the paper and applying pressure to said layer of rubber.

6. As a new article of manufacture, a cornposite sheet for use in making moisture-proof and substantially punctureproof packages, comprising two sheets of fibrous material bonded together solely by a homogeneous layer of highly elastic rubber deposited from an aqueous dispersion of rubber plastically applied to the material, said layer of rubber `being separable from said fibrous material by an object breaking through the material.

LLOYD G. COPEMAN. 

